Old Salt Mix Mystery Liquid

[Heathcliff37]

I encountered a truly bizarre phenomenon. By some unknown mechanism, my instant ocean salt mix is giving off some unidentified liquid. It is so crazy that I had to share my experience and see if anyone else could relate. The bag is a few years old, and a strange clear liquid forms around the bottom of the bag. The liquid gets created so rapidly and so greatly that it will drip and spread all over everything else where it is stored. I have to keep it wrapped up in plastic garbage bags, and when I take it out it forms a small puddle. I’ve wiped it dry and then a month later it is again soaked in this liquid. I have a bachelor’s degree in marine science, yet I cannot explain how this could be happening. The liquid has similar properties somewhat similar to propylene glycol. It is not water soluble and I have to use organic solvents ( i.e. alcohol) to clean it up. The inside of the bag seems moist, but there’s not a pool of the liquid, however the salt could just be acting like a sponge and absorbing it.

Does anyone have idea what the liquid could be or where it’s coming from? Has ANYONE else experienced this?

 

[ReeferHD]

probably the salt just absorbing the moisture in the air and then releasing it onto the floor happens with our bag of driveway salt sometimes

 

[Heathcliff37]

probably the salt just absorbing the moisture in the air and then releasing it onto the floor happens with our bag of driveway salt sometimes

That would make sense, but the liquid is not water, at least not pure water or saltwater. Like I said it acts like an organic solvent. perhaps there is one constitute that is dissolving in an uneven ratio, giving it unique properties, but I don't know what that could be.

 

[taricha]

If you take magnesium chloride hydrates and leave them out, they absorb so much water from the air the salts turn into a puddle. (At least in my southern humidity.)

 

[Randy Holmes-Farley]

What do you mean it is not water soluble?

If you take a few drops and add it to tap water or RO/DI, it makes a separate phase that will not dissolve even with significant stirring?

If that really happens, then it got contaminated with a solvent.

FWIW, I once was walking barefoot through my dining room in North Carolina in the summer time, and stepped in some water scattered about the wood floor. I was initially perplexed as I was certain we had not eaten in that room for months, and there were no pipes overhead to leak.

Finally I realized that some table salt had spilled, and each grain collected moisture onto it and around it and made a tiny puddle of salty water.
'
Same will happen with a salt mix when it is humid enough.

It turns out that saturated salts can be used to make constant humidity chambers, and if the humidity is higher than equilibrium for a given salt, water goes from the air to the initially dry and then wet salt.

Sodium chloride will absorb moisture as long as there is any solid remaining if the relative humidity is above about 75%. Magnesium chloride, a main component of salt mixes, liquifies if the relative humidity is above about 33%.

Saturated Salt Solutions - Controlling Air Humidity

A salt solutions can be used maintain a particular value of relative humidity.

www.engineeringtoolbox.com

 

[Heathcliff37]

What do you mean it is not water soluble?

If you take a few drops and add it to tap water or RO/DI, it makes a separate phase that will not dissolve even with significant stirring?

If that really happens, then it got contaminated with a solvent.

FWIW, I once was walking barefoot through my dining room in North Carolina in the summer time, and stepped in some water scattered about the wood floor. I was initially perplexed as I was certain we had not eaten in that room for months, and there were no pipes overhead to leak.

Finally I realized that some table salt had spilled, and each grain collected moisture onto it and around it and made a tiny puddle of salty water.
'
Same will happen with a salt mix when it is humid enough.

It turns out that saturated salts can be used to make constant humidity chambers, and if the humidity is higher than equilibrium for a given salt, water goes from the air to the initially dry and then wet salt.

Sodium chloride will absorb moisture as long as there is any solid remaining if the relative humidity is above about 75%. Magnesium chloride, a main component of salt mixes, liquifies if the relative humidity is above about 33%.

Saturated Salt Solutions - Controlling Air Humidity

A salt solutions can be used maintain a particular value of relative humidity.

www.engineeringtoolbox.com

I mean that it is not water soluble in that a wet cloth with not clean it up. Similarly a dry one absorb it either. I have to use a paper towel soaked in alcohol. The mystery liquid may technically be soluble if I directly drop it in RO water, I’m going to try this out of curiosity. I’m just confused because water or salt water normally would just wipe up like normal freshwater. If I spill saltwater on the floor I would never have to dissolve it on alcohol to clean it up. The liquid clearly behaves differently. I’m not 100% sure the bag isn’t contaminated, that’s possible. Regardless, it’s funny that so many other people are having similar experiences with salt producing puddles! I’d never heard of this being so extreme before!
My full hypothesis at this point is that the salt is both soaking up water from the air and releasing some solvent that it’s contaminated with. The water condensed from the air, mixed with the solvent, and then creates this solution.

Still could it be an ion or solute (potentially an impurity) in the salt that can similarly affect the properties of the resulting solution? I know this is extremely redimentary, but I know sugar dissolves in water makes a “sticky” solution. Couldn’t it be similar phenomenon? Some solute from the salt dissolving in the water to give it these properties? Perhaps some organic impurity?

 

[Dburr1014]

My magnesium chloride bag does the same thing. It always makes a puddle underneath it. It's absorbing the moisture from the air and just dumping it out the bottom of the bag.
Kind of like those dry sorb things you buy for the Attic. It pulls the moisture out of the air and dumps it into a little bucket underneath. All that stuff is I believe is magnesium chloride.

 

[Heathcliff37]

My magnesium chloride bag does the same thing. It always makes a puddle underneath it. It's absorbing the moisture from the air and just dumping it out the bottom of the bag.
Kind of like those dry sorb things you buy for the Attic. It pulls the moisture out of the air and dumps it into a little bucket underneath. All that stuff is I believe is magnesium chloride.

See, this is exactly what I suspected. It is probably magnesium chloride or something similar.
A Google search of “magnesium chloride slime” produced results of literal slime recipes using it. Similarly, I know roads use magnesium and other chlorides to salt roads and keep down dust and it forms a somewhat slime like substance.
So it’s probably that.
I’m still not sure why it’s so difficult to clean up using water. But at least we have a working hypothesis now! Perhaps it’s a combination of disolved solutes, some which may be impurities.

 

[Randy Holmes-Farley]

I mean that it is not water soluble in that a wet cloth with not clean it up. Similarly a dry one absorb it either. I have to use a paper towel soaked in alcohol. The mystery liquid may technically be soluble if I directly drop it in RO water, I’m going to try this out of curiosity. I’m just confused because water or salt water normally would just wipe up like normal freshwater. If I spill saltwater on the floor I would never have to dissolve it on alcohol to clean it up. The liquid clearly behaves differently. I’m not 100% sure the bag isn’t contaminated, that’s possible. Regardless, it’s funny that so many other people are having similar experiences with salt producing puddles! I’d never heard of this being so extreme before!
My full hypothesis at this point is that the salt is both soaking up water from the air and releasing some solvent that it’s contaminated with. The water condensed from the air, mixed with the solvent, and then creates this solution.

Still could it be an ion or solute (potentially an impurity) in the salt that can similarly affect the properties of the resulting solution? I know this is extremely redimentary, but I know sugar dissolves in water makes a “sticky” solution. Couldn’t it be similar phenomenon? Some solute from the salt dissolving in the water to give it these properties? Perhaps some organic impurity?

Very high salinity solutions (as will form in a salt exposed to moist air) will have a very high surface tension and that may make the paper towel thing harder. While the analysis is very complex and many papers on various models exist, High surface tension fluids do not enter small channels as readily. Alcohol will drop the surface tension of the liquid and make soaking it up easier.

IMO, there is no solvent here other than water.

https://core.ac.uk/download/pdf/217046725.pdf

"Low surface tension and low contact angle have been found to be advantageous to fast absorption of fluid."

 

[Randy Holmes-Farley]

See, this is exactly what I suspected. It is probably magnesium chloride or something similar.
A Google search of “magnesium chloride slime” produced results of literal slime recipes using it. Similarly, I know roads use magnesium and other chlorides to salt roads and keep down dust and it forms a somewhat slime like substance.
So it’s probably that.
I’m still not sure why it’s so difficult to clean up using water. But at least we have a working hypothesis now! Perhaps it’s a combination of disolved solutes, some which may be impurities.

I don't think it is anything more than a high salt solution.

Magnesium chloride readily hydrates, but it does not slime by itself in water. Wetting dirt makes mud, which is the dust control aspect. Calcium chloride is also used widely for dust control. It is used only because it collects moisture.

Calcium Chloride for Dust Control: All You Need to Know

A calcium chloride is a salt that provides excellent dust control. Learn how to apply calcium chloride for dust control and find out more about its benefits.

ninjadeicer.com

How Calcium Chloride Controls Dust​

Calcium chloride pellets are hygroscopic which means they attract moisture from the air and their surroundings. This property is how calcium chloride keeps the road’s surface damp which, in turn, helps keep the dust down. It also resists evaporation, which allows one application to last a long period of time, even on the hottest and driest of days.

 

[Dom]

I don't think it is anything more than a high salt solution.

Magnesium chloride readily hydrates, but it does not slime by itself in water. Wetting dirt makes mud, which is the dust control aspect. Calcium chloride is also used widely for dust control. It is used only because it collects moisture.

Calcium Chloride for Dust Control: All You Need to Know

A calcium chloride is a salt that provides excellent dust control. Learn how to apply calcium chloride for dust control and find out more about its benefits.

ninjadeicer.com

How Calcium Chloride Controls Dust​

Calcium chloride pellets are hygroscopic which means they attract moisture from the air and their surroundings. This property is how calcium chloride keeps the road’s surface damp which, in turn, helps keep the dust down. It also resists evaporation, which allows one application to last a long period of time, even on the hottest and driest of days.

I would be curious to know what the reading would be if you placed the solution on a refractometer...

 

[Heathcliff37]

I would be curious to know what the reading would be if you placed the solution on a refractometer...

Me too! I don’t currently own one but I’m tempted to buy one just for this.

 

[Heathcliff37]

I don't think it is anything more than a high salt solution.

Magnesium chloride readily hydrates, but it does not slime by itself in water. Wetting dirt makes mud, which is the dust control aspect. Calcium chloride is also used widely for dust control. It is used only because it collects moisture.

Calcium Chloride for Dust Control: All You Need to Know

A calcium chloride is a salt that provides excellent dust control. Learn how to apply calcium chloride for dust control and find out more about its benefits.

ninjadeicer.com

How Calcium Chloride Controls Dust​

Calcium chloride pellets are hygroscopic which means they attract moisture from the air and their surroundings. This property is how calcium chloride keeps the road’s surface damp which, in turn, helps keep the dust down. It also resists evaporation, which allows one application to last a long period of time, even on the hottest and driest of days.

At this point I agree that it’s just a high salinity solution.
I do suspect magnesium chloride or similar compounds are probably present in higher ratios than normal seawater, since I’ve observed that the liquid droplets will never evaporate even after 6+ months whereas normal seawater does fully evaporate.

Anyways, I’m so happy I posted this thread! It turned out much more scientific than I expected and I’m glad other people could relate. I’ve already learned some interesting points about the properties high salinity solutions, and the hygroscopic properties of salts. They don’t teach you these things in university chemistry courses!

 

[Randy Holmes-Farley]

Me too! I don’t currently own one but I’m tempted to buy one just for this.

i expect that for most Reefing models it will be off scale. It’s too salty.

 

[Randy Holmes-Farley]

At this point I agree that it’s just a high salinity solution.
I do suspect magnesium chloride or similar compounds are probably present in higher ratios than normal seawater, since I’ve observed that the liquid droplets will never evaporate even after 6+ months whereas normal seawater does fully evaporate.

Anyways, I’m so happy I posted this thread! It turned out much more scientific than I expected and I’m glad other people could relate. I’ve already learned some interesting points about the properties high salinity solutions, and the hygroscopic properties of salts. They don’t teach you these things in university chemistry courses!

It will likely have more magnesium relative to sodium than normal seawater because sodium chloride will hit its solubility limit before magnesium chloride.

 

[Dom]

Me too! I don’t currently own one but I’m tempted to buy one just for this.

 

[Heathcliff37]

I should start a go fund me

 

[Heathcliff37]

I'm resurrecting this to ask, is a salt mix that has absorbed that much humidity no longer advisable to use? I imagine many of the compounds have precipitated and formed insoluble compounds. Is it still advisable to use it for corals and such (sps, soft corals, etc) or do I need to get a new bag?

 

[Randy Holmes-Farley]

I'm resurrecting this to ask, is a salt mix that has absorbed that much humidity no longer advisable to use? I imagine many of the compounds have precipitated and formed insoluble compounds. Is it still advisable to use it for corals and such (sps, soft corals, etc) or do I need to get a new bag?

Yes, it is likely low in alk and calcium, and possible trace elements that precipitated into the depositing calcium carbonate.

If alk and calcium are OK, that is, like that brand normally is, it is likely OK to use.